U.S. patent number 4,591,784 [Application Number 06/452,030] was granted by the patent office on 1986-05-27 for examination procedure for the spatial change of an object with respect to its initial condition.
This patent grant is currently assigned to Bayerische Motoren Werke AG. Invention is credited to Jorg Kolitsch, August Miehle.
United States Patent |
4,591,784 |
Kolitsch , et al. |
May 27, 1986 |
Examination procedure for the spatial change of an object with
respect to its initial condition
Abstract
Technical functional components variable relatively to a
starting position are examined by comparing an image of the
component, produced by relative motion with respect to sensor
means, with a corresponding earlier, stored image, and by
triggering a warning signal in accordance with the congruence
and/or the differences of the two images.
Inventors: |
Kolitsch; Jorg (Munich,
DE), Miehle; August (Munich, DE) |
Assignee: |
Bayerische Motoren Werke AG
(DE)
|
Family
ID: |
25798257 |
Appl.
No.: |
06/452,030 |
Filed: |
December 22, 1982 |
Foreign Application Priority Data
|
|
|
|
|
Dec 24, 1981 [DE] |
|
|
3151265 |
Nov 5, 1982 [DE] |
|
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3240948 |
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Current U.S.
Class: |
324/207.25;
324/226; 340/680; 73/660; 324/227; 356/390 |
Current CPC
Class: |
G01M
13/00 (20130101); G01B 7/023 (20130101); G01B
7/28 (20130101); G01M 11/081 (20130101) |
Current International
Class: |
G01M
13/00 (20060101); G01B 7/28 (20060101); G01B
7/02 (20060101); G01M 11/08 (20060101); G01B
007/28 (); G01B 011/24 (); G01B 017/00 (); G01B
007/14 () |
Field of
Search: |
;324/207,208,226,227,224,232,233-243 ;73/660,661,761 ;356/390
;364/559,560 ;340/679,680 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Strecker; Gerard R.
Attorney, Agent or Firm: Craig and Burns
Claims
We claim:
1. A testing method for the configuration of technical functional
components, each component having a first axis of rotation, said
components being rotatable about a second axis, comprising the
steps of
successively rotating said components about said second axis,
sensing rotation about said first axis of an entire configuration
of each component during said successive rotations about said
second axis,
generating successive first signals in response to said sensing,
each of the successive first signals representing a sensed
configuration of the component,
comparing successive first signals for producing a second signal
representative of a change in an entire configuration of each of
said components resulting from rotation of a component about the
first axis during rotation about the second axis, and
triggering a warning signal in response to one of a congruence and
a difference in said first signals.
Description
The invention relates to a testing method and apparatus for
technical functional components variable relatively to their
starting position.
A process is known for quality control and indication of rejects in
the tightening of threaded connections wherein the instantaneous
values of torque and angle of rotation are determined in a number
of points during the tightening procedure and are compared with
predetermined torque-angle of rotation limit values. If these limit
values are exceeded, indicating signals are produced (DOS [German
Unexamined Laid-Open Application] No. 2,843,810). The conventional
process does not yield any information on the strength of the
threaded connection after completion of the tightening step.
The invention seeks to provide a testing method and apparatus for
technical functional parts which makes it possible, with simple
means, to give an indication of the position and/or positional
change of the functional component.
The invention attains this by providing that an image of the
component, produced by relative movement with respect to a sensor
means, is compared with a corresponding earlier, stored image; and
that a warning signal is triggered in correspondence with the
congruence and/or the differences of the two images.
The basic idea of the invention resides in drawing a conclusion,
from a comparison of the images of a technical functional component
at an earlier point in time and at the present point in time, with
respect to the movement or change in contour of the functional
component in the meantime, and deriving a warning signal therefrom,
if necessary. Possibilities for utilization are, for example, in
connection with the gear wheels of chain drive mechanisms for
testing, for example, wear and tear on the teeth; turbine buckets
for determining outward migration of the buckets due to centrifugal
forces, or bending due to cavitation; roller bearing cages;
furthermore automatic conveyors in underground or strip mining;
further wear of drilling and cutting tools; or testing of ram drive
mechanisms in machine tools and/or testing of cam-shafts.
A comparison of the two images of the component makes it possible
to recognize, in accordance with the resolution accuracy of the
sensor means and of the comparison means, a change in the
rotational position of this component and can yield a warning
signal at an early point in time at which this change is as yet
unrecognized, for example, by the human eye. On the other hand, a
missing warning signal in case of a screw connection, for example,
points to a high quality of the threaded connection and/or
generally to a high positional stability.
The testing method can be performed in various ways. For example,
the image can be produced at chronologically identical intervals.
After comparison, such image can be stored instead of the preceding
image. The earlier, storage image is thus always kept up to date.
If the warning signal, upon its occurrence, is not immediately
utilized for placing the component into the desired, original
position, the number of warning signals can then permit a
conclusion regarding the positional behavior of the component. An
alternative testing method wherein the original image of the
component forms the basis in all cases for the comparison, permits
an indication from the number of warning signals as to the point in
time that a positional error of the component occurred.
Various possibilities also exist for recording the images. As
contrasted to a movement of the sensor past the fixed component,
the reverse movement procedure offers advantages especially when
examining rotating components. For example, such a fixed sensor
means can also be provided subsequently at low cost.
Also the mode of operation of the sensor means can be based on
various principles. Thus, the images for a metallic component can
be produced by inductance. In this case, the sensor means is, for
example, a simple coil wherein a voltage signal is produced by the
component, lying above and below a medium value.
As an alternative, the images can also be produced, for example,
optically or acoustically. The wavelength of the optic or acoustic
signals transmitted by the sensor means can be outside of the
visible or audible range. In either case, it is possible, for
example, to determine the reflective characteristic of the
component, or the spacing thereof with respect to the sensor
means.
A device making it possible to conduct the process of this
invention with simple means comprises a single sensor as the sensor
means, this sensor being connected to a memory storage means.
It is thus an object of the invention to provide a method and
apparatus for the testing of the technical functional effectiveness
of moving components.
It is another object of the invention to provide method and
apparatus for sensing a change of position of a moving component
from which successive signals are generated representing repetitive
sensings of a change in position of the component from which a
display is produced of the signals whereby an indication of a
warning may be effected in response to a change in the received
sensed signals.
It is another object of the invention to produce method and
apparatus for indicating optically or acoustically a change in the
effectiveness of a moving component in response to sensed signals
at least one of which is stored.
It is another object of the invention to produce a warning
indication from a sensed signal of a change in configuration of a
moving component only when the change sensed exceeds a
predetermined value limit.
It is another object of the invention to produce a warning signal
when the number of changes of configurations of plural components
exceeds a predetermined limit.
It is another object of the invention to produce sensed signals of
the change in distance of a component from the sensor in order to
indicate a warning of a change in configuration of the
component.
These and other objects, features, and advantages of the present
invention will become more apparent from the following description
when taken in connection with the accompanying drawings which show,
for the purposes of illustration only, embodiments in accordance
with the present invention, and wherein:
FIG. 1 shows obtaining an inductive image of a component of a
threaded connection,
FIG. 2 shows a testing device, by means of which such images in
threaded connections are obtained at a rotating part and employed
for a warning signal,
FIG. 3 shows a testing device making it possible to monitor the
toothed rim of the flywheel for an automotive vehicle, and
FIG. 4 shows the images of the toothed rim of FIG. 3, obtained, for
example, by inductance, prior to and after a predetermined
operating period.
Before describing, in detail, the particular improved apparatus in
accordance with the present invention, it should be observed that
the present invention resides primarily in the novel structural
combination of conventional components and not in the particular
detailed configurations thereof. Accordingly, the structure,
control, and arrangement of these conventional components are
illustrated in the figures of the drawings by readily
understandable block representations in order not to obscure the
disclosure with structural details which would be readily apparent
to those skilled in the art having the benefit of the description
herein. Thus, the block diagram illustration of the figures of the
drawings do not necessarily represent the mechanical structural
arrangement of the exemplary system, but are primarily intended to
illustrate the major structural components of this system in a
convenient functional grouping so that the present invention can
more readily be understood.
Turning to the figures wherein like reference numerals represent
like parts, FIG. 1 shows the inductive images of three screw heads
1 through 3, produced while passing by an induction generator shown
schematically as a coil 4. The image corresponds to the voltage
induced in the coil 4 and is illustrated in correlation with the
screw heads 1-3. By comparing the height of spike A with spike B,
it can clearly be seen that the voltage peak produced by the corner
X of the screw heads 1-3 in the closest proximity to the coil 4 is
higher, the closer such a corner X is positioned with respect to
the coil 4.
The rise and drop characteristic of the voltage and the amplitude
and position of the voltage peaks relatively to the corresponding
values for the other screw heads make it possible to give a clear
indication regarding the rotational position of the screw heads
1-3, even directly in angular degrees. Upon a rotation of a screw
head, the characteristic image is likewise altered. This change is
utilized for triggering a warning signal by means of a device as
schematically shown in FIG. 2.
The device makes it possible, for example, to test screw
connections at the ring gear 7 or a rear axle transmission for
automotive vehicles. The device consists of an inductance generator
4' corresponding to coil 4 of FIG. 1, fixedly arranged in the
proximity of the screw heads 1-3 and 5 and 6 of the ring gear 7.
The inductance generator 4' is connected to an analog/digital data
processing system 8 comprising an analog-to-digital converter 9, a
central unit 10, a memory 11, and a picture screen 12.
The converter 9 digitizes the images of the screw heads supplied
according to FIG. 1 by the inductance generator 4' and transmits
these data to the central unit 10.
Those skilled in the art will understand that sensing may take
other forms than the inductance coil 4 shown in FIG. 1. Thus, an
optical configuration may be used wherein a light source transmits
light to the sensed member. Reflected light from the member is
received at a photocell, the analog output signal of which is input
to the analog/digital converter 9. Irregularities in the reflected
and received signals due to a change in the parts sensor will
result in corresponding irregularities in the signal digitized by
converter 9.
At the beginning of the testing operation, the central unit 10
feeds these digitalized images of the screw heads into the memory
11. At chronologically regular intervals, the images of the screw
heads 1-6 present at the ring gear 7 are now recorded during a
complete revolution of the ring gear 7. The use of a trigger unit
13, which generates a synchronizing pulse at a fixed point, in each
revolution of ring gear 7, ensures that the series of these images
is always the same. The central unit 10 receives these
instantaneous images of the screw heads 1-6 and compares same with
the corresponding earlier images contained in the memory 11. In
case of lack of congruence of one or several of these images with
the corresponding, stored image, the central unit 10 produces a
warning signal, on the picture screen 12, for example, an
indication representing the form of the number of the loosened
screw connections.
The invention permits continuous monitoring of screw connections
for investigations regarding operational strength or prevention of
damage in machines and installations. The invention makes it
possible to recognize a twisting of the screws at even small
angular degrees and aids in avoiding unnecessary repair and idle
times for servicing operations as well as safety risks connected
therewith. The corresponding device operates in a no-contact mode.
Since the sensor can be fixedly mounted, no signal transmission
from the sensor is required (such as a slip ring transmitter, for
example). The invention can be utilized in all those cases where
screw connections at rotationally or translationally moved parts
represent a safety risk or a danger of failure, for example,
besides utilization in an automotive vehicle, in turbines in power
plants and in airplane engines. The warning signal can also be
provided in such a way that the machine or installation is forcibly
arrested upon the occurrence of an excessive change in the
rotational position of the monitored screw or securing
component.
The flywheel 21 for an automotive vehicle, shown in a fragmentary
view in FIG. 3, carries teeth 22 at regular intervals along its
circumference; these teeth are engaged by a pinion, not shown, of a
starter motor. An image 22', FIG. 4, of the teeth 22 is obtained
upon rotation of the flywheel 21 with the aid of an inductance
generator, shown schematically as a coil 4 and being fixedly
mounted. This image 22' is shown in the left-hand portion of FIG.
4, for example, for the newly manufactured state of the flywheel 21
and of the teeth 22. After a predetermined operating period, the
images of the teeth 22 are again recorded. FIG. 3 shows in dashed
lines a damaged tooth 23, produced in the meantime, for example, by
improper meshing of the starter pinion. The image obtained with the
aid of coil 4, as illustrated in the right-hand portion of FIG. 4,
differs with respect to the earlier image at the point 23'
corresponding to the damaged tooth 23. With the aid of an
analog/digital data processing system 8, a determination can be
made, with a comparison of the two images reproduced in FIG. 4, of
which tooth 23 is defective, and of the extent of such defect. The
latter can be derived in first approximation from a comparison of
the amplitudes of the corresponding output signals of coil 4 in the
two images for the damaged tooth 23.
If the thus-discovered defect, or the number of defective teeth,
exceeds a predetermined extent, an optical or acoustical warning
signal can be triggered.
It will be appreciated to those skilled in the art that the central
unit 10 as shown in FIGS. 2 and 3 may take a variety of forms. As
an example, a micro-processor may be employed. In one form, it may
consist of one or more chips, the electronic architecture of which
includes input and output circuitry, an arithmetic unit admitting
of at least four-function arithmetic operations with attendant
logic operations, memory and a program control unit. Such a
configuration may be tailored to the particular test configuration
desired with pre-stored program and data representing the data
characteristics required for testing.
Advantageously, such a configuration may also admit a manual
control whereby the program and data may be changed, if desired, by
way of a keyboard.
While higher level languages, such as FORTRAN and BASIC may be
used, characteristically, economy of memory use and increased speed
may be effected by the well known expedient of employing a
lower-level language such as ASSEMBLY language or MACHINE language
peculiar to the particular processor used.
Choice of architecture for the micro-processor, with language and
programming technique, it will be recognized, is within the skill
of those working in the art, and accordingly, the details thereof
will not be introduced to this disclosure except insofar as the
nature of the invention requires.
In the exemplary configuration of the invention shown in FIGS. 1-4,
damage may occur to bolt heads 1-6 of FIG. 1 (teeth 23, FIG. 3)
which is sufficiently minor so as not to necessitate the triggering
of a warning signal. Accordingly, a value I representing a
threshold degree of damage allowable, may be stored in the memory
of central unit 10 against which the received signals may be
compared to determine whether a warning signal must be
triggered.
Further, where a few, for example, one or more, bolt heads 1-6 (or
teeth 23) may be significantly damaged, it may be desirable to set
a limit II of the number of elements damaged (or changed) in a ring
gear as a threshold value to signal a further warning. Such a
number II may be stored in an additional storage register in the
memory of the central unit 10.
The operation of the central unit 10 may thus take the form of a
series of steps programmed to process incoming data as follows:
(1) By means of an input keyboard, the limit values I, representing
a threshold degree of damage for a single bolt head (or other
elements sensed) and limit value II presenting the number of
damaged bolt heads or teeth (or other elements sensed), are set
into respective storage registers for these values. Alternatively,
the input values may be stored during chip manufacture.
(2) Upon the receipt of a pulse from trigger unit 13, FIG. 2, the
central processing unit (CPU) of the central unit 10 stores
successive values for the signals received from inductance
generator 4' representing the successive passes of the elements, or
screw heads, 1-6 (teeth for FIGS. 3 and 4) in front of inductance
generator 4', in memory.
(3) At a subsequent occurrence of a pulse from trigger unit 13, a
new set of digitized signals from inductance generator 4'
representing subsequent passes of the bolt corners X for bolts 1-6
are recorded in memory. While the central unit 10 may store
individual values representing a magnitude of the peaks at points A
and B, it will be appreciated that an alternative mode may comprise
sensing multiple values which occur between the peaks. Thus, as
shown in FIG, 1, values of the signal may be sensed at points
A.sub.1, A.sub.2, A.sub.3 -A.sub.9, A. In this mode, ten values
would be stored for each signal, the sum of which represents the
time integral under the curve. While ten divisions have been
disclosed, those skilled in the art will recognize that this is
exemplary only, and that any number of time divisions may be
selected.
The values so stored may then be used to display a graphical image
on the picture screen or cathode ray tube, a graphical image such
as that shown in FIG. 4.
In a configuration where, as described above, multiple samplings
A.sub.1 -A.sub.9, A, have been stored, all such values may be
summed to produce a value which is representative of one cycle such
as 22', corresponding to the cycle A. A comparable summing of the
signals for the B cycle will produce a value representative of
B.
It will be appreciated that the time between the storing of
corresponding data of steps 2 and 3 may represent immediately
succeeding revolutions of the ring gear 7, as would be effected if
continuous monitoring is desired. Alternatively, a significant
amount of time may lapse between the two successive samplings of
data, for example, a period of one hour, a day, week or month, or a
longer period may be effected. At this point, the memory of central
unit 10 has corresponding sets of data representing the passages of
bolts 1-6 (or teeth, FIGS. 3 and 4) past inductance generator 4'.
If, during the time lapse between the two sensing cycles, damage
has occurred to one or more of the members 1-6, the data stored
will not match.
(4) The arithmetic unit of central unit 10 compares the digital
values for corresponding passes of the same element, thus, the
digital values stored in memory for the first and successive passes
of screw head 1 are compared, that is, subtracted. If the digital
value for the later pass is less than the digital value for the
first pass, the difference represents a changed bolt head, FIG. 1,
or damaged tooth, FIG. 4.
(5) The stored values for the A cycle and the B cycle, when
presented visually on the picture screen 12, FIG. 2, serve as an
alarm if any of the cycles, for example, the B cycle, deviate from
the norm.
Alternatively, the CPU of central unit 10 may serve to activate a
separate alarm, optical or acoustical. For this purpose, the CPU of
central unit 10 may compare the difference value determined in step
(4) with the limit value I stored in step (1). If this subtraction
step produces a zero or a plus value, this indicates that the
damage to the tooth in question does not exceed the limit I and
accordingly, the CPU transmits no alarm.
(6) If, on the other hand, a negative value is the result of the
comparison in step (5), the CPU of central unit 10 may activate a
first alarm indicating damage or change for a single bolt head (or
tooth). The CPU will record a "1" in a storage register in memory
set aside to record the number of bolt heads or teeth damaged, or
changed in a particular revolution. If in a single revolution in
the ring gear 7, one, two or three bolt heads exceed the limit I, a
corresponding value 1, 2 or 3, will stand in the storage
register.
(7) At the receipt of a subsequent signal from trigger unit 13
after the second pass of the ring gear 7, the value standing in the
storage register referred to in step (6), is compared with the
limit value II standing in the II register. By subtracting the
storage register value from the limit value II, if the result is
zero or a plus value, the limit has not been exceeded, and
accordingly, the CPU activates no alarm.
(8) If, on the other hand, a negative value results, this
represents the fact that the number of bolt heads or teeth damaged
exceeds the threshold value set and a warning signal to this
effect, either optical or acoustical, may be actuated by the
CPU.
The CPU may issue warning signals for both a single tooth or for a
total number of teeth damaged as the artisan may desire merely by
generating an output to the warning device in step (5) (or step
(7)) or both.
While we have shown and described only one embodiment in accordance
with the present invention, it is understood that the same is not
limited thereto but is susceptible to numerous changes and
modifications as known to one having ordinary skill in the art, and
we therefore do not wish to be limited to the details shown and
described herein, but intend to cover all such modifications as are
encompassed by the scope of the appended claims.
* * * * *